abstractthe essential oils of composition obtained from the leaves of cryptomeria fortunei, collected at different seasons in wuhan (china), were analyzed by gas chromatography (gc) gc-mass spectrometry (gc-ms). fifty constituents were identified, constituting 92.3-97.7% of the essential oils. our results showed that seasonal differences did not have an effect on the composition of oils but on the amount of oil components. the main components of the oil were kaur-16-ene (30.9-42.4%), elemol (16.8-18.9%), -eudesmol (7.4-13.6%), -pinene (1.9-8.0%) and -eudesmol (4.0-7.5%). on the basis of the results obtained, some suggestions are made concerning the optimal season for the c. fortunei oils.keywords: cryptomeria fortuneiessential oil compositionseasonal variationkaur-16-eneelemol acknowledgementsthis study was supported by the fundamental research funds for the central universities (2010py065). we thank hong cheng (science & technology analytical and testing center of huazhong university) for assistance in the gc-ms analysis.